1. Field of the Invention
The present invention relates to a communication apparatus which can be connected to ISDN (Integrated Services Digital Network), a method for controlling the same, and a computer-readable storage medium storing a program for the control.
2. Related Background Art
In communication by the use of a terminal (G4 facsimile etc.) connected to an ISDN, a fall-back function has been realized in a conventional facsimile apparatus as an example of such a control method that in a case where a partner apparatus is called with specification of a communication mode (G4·unrestricted digital mode, etc.) in a B-channel thereof, if the communication mode matches, the communication goes on, while if call connection with the ISDN fails due to a mismatch in the communication mode, etc., the communication mode is automatically switched to another mode (G3·3.1-kHz audio mode, etc.) to repeat the procedure.
In the above-mentioned conventional example, however, if call connection with the ISDN fails due to, for example, a mismatch in communication mode (a case where the partner is in a G3·3.1-kHz audio mode when it is called with specification of the G4 non-restricted digital mode, etc.), a fall-back function switches the communication mode into another (G3·3.1-kHz audio mode, etc.) to immediately shift to the call procedure again, so that it may sometimes take too long a time for the partner apparatus, exchanger, or network to be released and thus the partner cannot respond even when called again (i.e., it is in no condition to respond to the calling), whereby the call connection may be impossible even when the communication mode matches.